Discernment, the service and duty of the priests

Priesthood being established, there comes the discernment
between holy things and profane, and the judgment of defilements
(chaps. 11-15), and what was to be done for the purification of
defiled persons. We see that it is this nearness of separation
unto God which alone can discern thus, and such is the service
and ever the duty of priests.

Discernment of what was clean in food

First, as to food, that which is allowed to be eaten. In
general the principle seems to be, that anything is allowed that
is clean, in this sense, first, that it is thoroughly according
to its element, that is, in principle, divine order (of course
here presented in a figure), as fishes having scales; secondly,
that was allowed which united mature digestion to the absence of
that wilful energy which goes boldly through everything. These
two qualities must be united. The grossness which swallows down
things as they are, or the lack of quiet firmness, rendered
unclean. To be clean, it must be that which at the same time
chews the cud and divides the hoof. Of birds, the carnivorous
night birds and those which cannot be tamed are forbidden;
creeping things also, whatever grovelled and trailed itself on
the earth. In general, there was to be in their eating the
discernment of what was clean.

God's judgment on what, as now connected with sin, is
unclean

Then we have the judgment of God fallen on that which would
have been, for unfallen man, joy and blessing. The birth of a
man, connected now with sin, renders unclean; that of a woman, in
whom was the transgression, being deceived, still more so [1]
.

[1] Connected with this was the weakness of fallen nature
(compare Gen. 1: 2). All that belonged even to weakness of
nature, being the effect of sin, rendered unclean under the
law. This is also true spiritually. All this was the result of
some manifestation or other of the life that was in the flesh.
It was so with the leper; raw flesh rendered unclean, as well as
any other case where this life (which had become unclean, and had
been as set aside and under judgment through sin), manifested
itself externally, even though weakness alone were the cause of
its manifestation.